GHSA-XXFX-9M42-X999
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: RFCOMM: serialize security confirmation handling
rfcomm_security_cfm() looks up a session on session_list and then walks its DLC list without holding rfcomm_mutex. Since RFCOMM session teardown uses rfcomm_mutex, krfcommd can close and free the same session and DLCs concurrently:
hci_rx_work krfcommd ----------- --------- rfcomm_session_get() rfcomm_lock() rfcomm_session_close() rfcomm_dlc_unlink() rfcomm_session_del() kfree(s) rfcomm_unlock() walk s->dlcs
The callback can then read a freed session list head and touch freed DLCs while updating their flags or timers.
Serialize the session lookup and DLC traversal in rfcomm_security_cfm() with rfcomm_mutex. This matches the existing RFCOMM session lifetime rules and prevents concurrent rfcomm_session_del() / rfcomm_dlc_unlink() from tearing the objects down while the callback is using them.
KASAN reported:
BUG: KASAN: slab-use-after-free in rfcomm_security_cfm+0x41c/0x440 Read of size 8 at addr ffff888111fb3960 by task kworker/u17:1/89 Workqueue: hci0 hci_rx_work Call Trace: rfcomm_security_cfm+0x41c/0x440 hci_encrypt_cfm+0x139/0x590 hci_encrypt_change_evt+0x37b/0xc40 hci_event_packet+0x71b/0xb20 hci_rx_work+0x293/0x730 Allocated by task 69: rfcomm_session_add+0x9e/0x2f0 rfcomm_run+0x44b/0x41e0 Freed by task 69: kfree+0x131/0x3c0 rfcomm_session_del+0x188/0x220 rfcomm_run+0x1985/0x41e0
{
"affected": [],
"aliases": [
"CVE-2026-89569"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:40Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: RFCOMM: serialize security confirmation handling\n\nrfcomm_security_cfm() looks up a session on session_list and then walks\nits DLC list without holding rfcomm_mutex. Since RFCOMM session teardown\nuses rfcomm_mutex, krfcommd can close and free the same session and DLCs\nconcurrently:\n\n hci_rx_work krfcommd\n ----------- ---------\n rfcomm_session_get()\n rfcomm_lock()\n rfcomm_session_close()\n rfcomm_dlc_unlink()\n rfcomm_session_del()\n kfree(s)\n rfcomm_unlock()\n walk s-\u003edlcs\n\nThe callback can then read a freed session list head and touch freed DLCs\nwhile updating their flags or timers.\n\nSerialize the session lookup and DLC traversal in rfcomm_security_cfm()\nwith rfcomm_mutex. This matches the existing RFCOMM session lifetime\nrules and prevents concurrent rfcomm_session_del() / rfcomm_dlc_unlink()\nfrom tearing the objects down while the callback is using them.\n\nKASAN reported:\n\n BUG: KASAN: slab-use-after-free in rfcomm_security_cfm+0x41c/0x440\n Read of size 8 at addr ffff888111fb3960 by task kworker/u17:1/89\n Workqueue: hci0 hci_rx_work\n Call Trace:\n rfcomm_security_cfm+0x41c/0x440\n hci_encrypt_cfm+0x139/0x590\n hci_encrypt_change_evt+0x37b/0xc40\n hci_event_packet+0x71b/0xb20\n hci_rx_work+0x293/0x730\n Allocated by task 69:\n rfcomm_session_add+0x9e/0x2f0\n rfcomm_run+0x44b/0x41e0\n Freed by task 69:\n kfree+0x131/0x3c0\n rfcomm_session_del+0x188/0x220\n rfcomm_run+0x1985/0x41e0",
"id": "GHSA-xxfx-9m42-x999",
"modified": "2026-09-14T15:32:29Z",
"published": "2026-09-11T21:31:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89569"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1b7841ffad08e911e8c4b9470f3fa08423568940"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3873f3449701b3dc98cba577923be6493598e7a1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/62ce8b33eb238cf18c15207332fbdc26d858f592"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/759c185d0bbdb131357408f50b8735e04ed3caff"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7ded3264106418c6456ccceaafd9fda596ce12c3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/82425b14f0fb22e46cfddc56d6465570f5ed0ce6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/946d76db77ee5f922968ce558629ae47b381e3fc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fbf7961964a6e93360179f64712320ae9a1e9577"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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